Condenser-timed relay interrupter



July 27, 1954 'FIG] R. P. BOYER, JR

CONDENSER-TIMED RELAY INTERRUPTER Filed May 29, 1951 1 b 4% 8 InINVENTOR'. RICHARD P. BOYER JR.

BYM J- M0717 ATTORNEY Patented July 27, 1954 OONDENSER-TIMED RELAYINTERRUPTER Richard P. Boyer, Jr., La Grange, Ill., assignor,

by mesne assignments, to International Telephone and TelegraphCorporation,

tion of Maryland a corpora- Application May 29, 1951, Serial No. 228,810

' 2 Claims.

This invention relates to condenser-timed relay interrupters and moreparticularly to relay-type multi-step interrupters adaptable for use inautomatic telephone equipment.

It is an object of the present invention to provide a simple andeconomical electrical interrupter flexibly adaptable to the control ofcyclic circuit functions.

Another object is to provide a multi-step sequential interrupter inwhich the time between steps may be individually adjusted to provide anyone of a wide range of timing cycles.

A further object is to provide a multi-step circuit interrupter in whichas many steps may be incorporated as may be needed to meet any of a widevariety of specific circuit applications.

It has been found that relay-type interrupters efficiently capable offulfilling th above objects may be attained by utilization of circuitarrangements in which both the charge and discharge characteristics ofcondensers are used for timing purposes. Briefly, each of the basiccircuit arrangements herein disclosed for accomplishing the desiredresults, in general, require merely a condenser and one or more pairs ofrelays. The relays are so arranged that all are first pulledin in quicksuccession, and are then allowed to restore successively at timesdependent upon the rate of change of the charge on the condenser.

The first relay of each pair restores in its proper sequence when thedischarge current flowing through it from the condenser drops to therestoring value of the relay. Upon restoration of the first relay, thecondenser is arranged to be recharged through the second relay, duringwhich period the second relay is maintained operated until the chargingcurrent drops to the restoring value of that relay.

A feature of the invention lies in the fact that each of the basiccircuits may be extended to increase the number of steps in its cycle ofoperation to meet any of a large variety of specific needs by addingpairs of relays until the desired number of steps are provided. Such anextended circuit, like the basic circuits, is operated by pulling in allof its relays in quick succession at the start of the cycle, followingwhich, all are restored in succession at times determined by the currentvalues at which the individual relays restore and the rate at which thecharge on a common condenser is permitted to change during each step ofthe cycle.

Another feature of the invention resides in the fact that it may bearranged to be stopped at any instant during the cycle, or may be soarranged that each initiated cycle will continue to completion before itcan be stopped.

Still another feature of the invention is that the timing cycle may begoverned by a single condenser common to all relays of the circuit andmay incorporate as many steps as desired, each individually adjustableto provide the timing desired before the next succeeding step in thecycle is effected.

Other objects and features of the invention will become apparent as thedescription progresses.

Referring now to the drawings.

Fig. 1 shows a basic two-relay, condenser timed interrupter circuitembodying the principles of the present invention.

Fig. 2 shows another form of two-relay condenser timed circuit, modifiedo'ver the circuit shown in Fig. 1 in the manner in which the first relayof the cycle is initiated.

Fig. 3 is still another embodiment of the invention, differing from thecircuits of Figs. 1 and 2 in that the cycle may be initiated by a merepulse of voltage.

Fig. 4 shows a variation of the basic 2-relay timed interrupter circuitin which a third relay is utilized to halt operation of the circuitafter completion of one cycle of operation whereupon the start relaymust be released before another cycle can be started.

Fig. 5 is another circuit comprising an extension of the basic two relaytimed interrupter circuit having twice as many steps in its cycle as inthe basic circuits.

Wherever a terminal is shown at the apparent end of a circuit path, witha negative polarity mark associated therewith, a connection to theungrounded negative pole of a grounded battery, or other source ofdirect current (not shown), is thereby intended.

In the embodiment of the invention shown in Fig. 1, the condenser Ill isnormally retained in charged condition by being connected across thebattery or direct current source through break contacts I of start relaySI and a current limiting resistance I I. When the start relay SI isoperated by means external to the circuit (not shown), the condenser I0is placed in series with the winding of relay Al through the makecontacts of start relay SI and the break contacts of the break-makecontact set 2 of relay Bl, whereupon the condenser IO begins todischarge, supplying discharge current to the winding of relay Al andcausing it to be pulled in.

Upon operation of relay Al, closure of its make :2 contact set 2 forms aholding path for the relay by connecting its winding directly in serieswith the condenser it through the contact set 2, independent of theenergizing path already estab lished through the break contacts ofcontact set 2 of relay Bl.

Operation of relay Al energizes relay Bl by closing the make contacts ofthe make-beforebreak contact set of relay Al, which connects the windingof relay Bi between battery and ground through a current limitingresistance i2.

As soon as relay B! is operated, the break contacts of break-makecontact set 2 opens the ex ternal energizing path for relay A! andcauses relay Al to be energized solely through its own holding paththrough which the condenser its discharges. Relay A! remains operated solong as the discharge current of condenser it remains above the releasevalue-of relay Al. When such current diminishes to the value at whichrelay Al restores, it disconnects its own holding circuit through themake contacts of contact set 2, and opens the energizing circuit forrelay Bl at the make contacts of the make-before-break contact set 3.Before disconnecting the energizing circuit, however, it places thecondenser ill in series with relay Bi by closure of the break contactsof the contact set 3. The condenser can then be charged through the pathformed by the winding of relay Bi, the break contacts of contact set 3of relay Al, and the make contact set 2 of relay Bi, which are connectedto the condenser it through the contact set i of start relay SI. Thevalue of charging current for the condenser ill flowing through thewinding of relay B! is initially high, but it diminishes gradually asthe condenser becomes charged until the restoring value of relay Bl isreached, whereupon relay B! is restored to make the circuit ready foranother cycle of operation.

In this circuit, as long as the start relay SI is energized, cyclicoperation of the circuit will continue, and the condenser willalternately discharge through the winding of relay A! and become chargedagain through the winding of relay Bl. If the start relay Si isdeenergized at any point in the cycle, the circuit is restored to itsnormal condition ready to be initiated again.

In the modification of the invention shown in Fig. 2, the circuit isarranged so that the period of the cycle may be lengthened over that ofthe circuit of Fig. 1, by arranging the condenser 22 so that it becomesconnected in series with a relay A2 after the relay has been operated byenergy supplied independently of the charge on the condenser. The chargeon the condenser is thus used solely for controlling the time ofoperation of relay A2, rather than being partly consumed for operationof relay A2. In other words, the period for which the first timing relayis maintained operated, after once being initiated, may be lengthenedconsiderably with the circuit arrangement of Fig. 2, since none of thecharge on condenser 22 is initially consumed in operating relay A2. Thiscircuit, like that of Fig. 1 may be stopped at any time by deenergizingthe start relay.

The operation of this circuit is initiated by a start relay S2 whichapplies ground to the winding of relay A2 through the make contact set 2of relay S2 and the break contact set 3 of relay B2. Relay S2 alsocauses the condenser 22, which is normally maintained in chargedcondition between connections to battery and ground through the breakcontacts of a break-make contact set i of relay S2 and a currentlimiting resistance 2!,

to be connected to the back contact of the make contact set 2 of relayA2, preparatory to providing a holding path for relay A2 when itoperates.

When relay A2 is operated, its holding path is formed by closure of itsmake contact set 2 through which the condenser 28' may be discharged.The condenser 26, however, will not discharge through this holding pathuntil the ground connection to the winding of relay A2 establishedthrough the make contacts 2 of start relay S2, is opened at the breakcontacts 3 of relay B2. Operation of relay A2 causes relay B2 to beoperated by closing the make contacts of the make-before-break contactset 3 of relay A2, thereby energizing the winding of relay B2 betweenground and battery through a current limiting resistance 22. Relay B2 isthereby made to operate almost immediately following the operation ofrelay A2.

The opertaion of relay B2, in being eiiective to remove ground potentialfrom the winding of relay A2, permits condenser 28 to start dischargingthrough the winding, thereby keeping relay A2 in operated condition fora period governed by the time required for the condenser dischargecurrent to reduce to the restoring value of the relay. Relay B2 alsoacts to prepare a holding path for itself through its own break contactset 2 which becomes effective when the condenser is placed in serieswith the relay winding through the break contacts of contact set 3 ofrelay A2, when relay A2 restores.

When the discharge current of condenser 20 diminishes to the restoringvalue for relay A2, the holding circuit for the relay is opened at itsmake contacts 2, and in addition, the energizing path for relay B2through the make contacts of contact set 3 is also opened. Before theenergizing path for relay B2 is opened, however, the condenser 20 isplaced in series with its winding through the break contacts of thecontact set 3 of relay A2 so that it will continue to be held inoperated position by the condenser charging current flowingtherethrough. Relay B2 will thus be maintained operated for a timefollowing restoration of relay A2 dependent upon the time required forthe charge on the condenser to build up through the holding path ofrelay B2. When the condenser charge reaches a point where the chargingcurrent has diminished to the value at which relay B2 restores, its makecontacts 2 open the path leading to condenser 20, while its breakcontacts 3 are closed so that ground again may be placed on the windingof relay A2 to reinitiate the cycle.

In the embodiment of Fig. 3, the timing condenser 30 is so arranged withrespect to the windings of the relays A3 and B3, that if the start relayis ole-energized. at any time during the cycle of operation of thecircuit, the cycle will not be halted, but will continue until all stepshave been completed, and only at such time will the circuit be ready forreoperation. Thus, only a pulse of voltage is required to initiate acycle of operation of this circuit, but if desired, continuous operationof the circuit can be effected by application of a constant ground tothe start relay S3.

Upon operation of the start relay S3, ground potential is applied to oneside of the winding of relay A3 through the make contacts 5 of the startrelay and the break contacts 2 of relay B3. Voltage is thus applied torelay A3 and it operates almost immediately following initial operationof the start relay.

Operation of the relay A3 causes the charged condenser 30 to be placedin series with its winding through the make contacts of its break-makecontact set 2. Condenser 30 is normally charged over the path formed bythe break contacts of the contact set 2, the contacts 3 of relay B3, andthe current limiting resistance 3!. Operation of the relay A3 is alsoefiective in energizing the winding of relay B3 between battery andground and through the make contacts of the makebefore-break contact set3 of relay A3, as well as through the current limiting resistance 32.

When relay B3 operates, it disconnects ground from the winding of relayA3 by opening its break contacts 2. As long as the break contacts 2 ofrelay B3 remain closed, the condenser is maintained in charged conditionbecause ground is applied to the condenser through the make contacts Iof the start relay S3 and the mak contacts of contact set 2 of relay A3.The timing for relay A3, therefore, does not begin until the contact set2 of relay B3 is opened. Operation of relay B3 also opens its breakcontacts 3 thereby opening the initial charging circuit for thecondenser 30. Thus, when contact set 3 of relay B3 is opened,restoration of the break contacts of the make-break contact set 2 ofrelay A3 will not cause condenser 30 to be supplied with chargingcurrent. As long as the start relay S3 is maintained operated suchcurrent can be supplied only through the winding of relay B3. Theclosure of the make contacts 4 of relay B3 places the condenser 30 inseries with the break contacts of the ma-ke-before-break contact set 3of relay A3 preparatory to the charging of condenser 30 upon restorationof relay A3.

When the discharge current of condenser 30 passing through the windingof relay A3 diminishes sufliciently, relay A3 restores, thereby openingthe break contacts of its makebefore-break set 3, and placing thecondenser 30 in series with the winding of relay B3 through which thecondenser may again be charged. As long as the charging current is high,the relay B3 remains operated, but as soon as it diminishes to a lowenough value, the relay restores. The rate at which condenser 33 becomescharged, and consequently the period required for relay B3 to berestored, is dependent upon the resistance, inductance and capacitancein the path of which it is a part.

Upon restoration of relay B3, its contact set 2 closes again to connectthe ground through the contact set i of start relay S3 to the winding ofrelay A3, thereby causing the circuit to be recycled. If, however, atany time during the operating cycle, the ground connection through thestart relay S3 is disconnected, it will be noted that the cycle willcontinue until completion, since relay A3 has its own holding paththrough the make contacts of the make-break contact set 2. Relay A3 willthus be kept operated until condenser 30 is discharged, after whichoperation of relay B3 will continue by reason of the condenser 30 beingcharged through its winding, In other words, the operating cycle afteronce being started, becomes independent of the ground on the start relayS3.

Fig. 4 shows a modification of the basic circuit shown in Fig. 1 inwhich an additional relay C4 is provided to prevent re-cycling followingthe first cycle of operation unless the start relay S4 is firstrestored. This circuit utilizes the basic circuit arrangement of Fig. 1,and accordingly may be stopped at any time during the cycle byde-energizing the start relay S4, but unlike the basic circuitarrangement, if the cycle is permitted to continue to the last step, thecircuit will not re-cycle until the start relay S4 is first restored andthen reinitiated. The relays A4, B4, and C4 are drawn up in quicksuccession, but after relay A4 and relay B4 have been restored followingtheir timed period of operation, relay C4 will continue to be heldoperated. Operation of relay A4 and B4 is like that of the correspondingrelays Al and BI in the circuit of Fig. 1, but the basic arrangement ischanged slightly in that the lead 43 connected to the back contact ofthe make-break contact set 2 of relay B4 is connected to the break.contacts 2 of relay C4 before returning to the make contacts 2 of relayA4. Additional make contacts 4 of relay A4, and make contacts 3 of relayB4 are provided to connect ground to relay C4 after relay A4 and B4 havebeen operated. After operation of relay C4, however, a pair of makecontacts 3 of its own, causes it to hold itself until the start relay S4is deenergized.

Thus, it will be seen that when relay C4 operates, the break contacts 2thereof open the current path through which condenser 40 can operaterelay A4, and even though the charged condenser may be connected to thefront contact of the contact set I of the start relay S4, the relay A4cannot be energized again until the break contacts 2 of relay C4 areclosed. Such closure of contacts 2 of relay C4 can be effected only whenthe start relay S4 is first de-energized.

The circuit of Fig. 5 shows the manner in which the basic circuit may beextended to provide an increased number of timing steps as desired.Broadly, the relays of this circuit are all drawn up succesively andthen successively restored by aletrnate discharge and charge of thecondenser 50. Upon restoration of the last relay, the circuit is againready for recycling as in the basic two relay interrupter. It will beapparent that such an extension is not limited to only four steps oftiming, but may be extended to include as many additional pairs of stepsas might be required for any particular application.

The condenser 50 of this circuit is normally charged between battery andground through the break contacts I of the start relay S5 and thecurrent limiting resistance 5|. When the start relay S5 is operated thecondenser is placed in series with the winding of relay A5 through thebreak contacts of contact set 2 of each of the relays B5, C5, and D5 tooperate relay A5.

When relay A5 operates, it provides a holding path for itself throughthe make contacts of its own contact set 2 so that it will be maintainedoperated as long as suflicient current is supplied from the condenser53. The make contacts of the make-before-break contact set 3 of relay A5also closes to energize the winding of relay B5 through the currentlimiting resistance 52.

When relay B5 is operated it opens the break contacts 2 of thebreak-make set 2 of relay B5,

7 and prepares the series circuit for the condenser with the winding ofrelay B5 through the make contacts of the break-make contact set 2 ofrelay B5.

Similarly, relays C5 and D5 are operated successively upon operation ofthe contact set 3 of relay B5 and contact set 3 of relay C5,respectively.

It will be noted that relay A5 of this circuit is the only one which isinitiated by the charge on the condenser 50, while the rest of therelays, namely relays B5, C5, and D5 are each operated byseparatecircuits established by closure or the contact of the relays precedingthem in operation. Thus, the timing of the relays following the firstare each independent in their operation. If, however, it is desired, thefirst relay in the series may also be made independent in its operation,by connecting the'first relay to ground in the manner shown in Figs. 2and 3.

It may be that the time constant of the discharge circuit for condenser50 through relay A5. is such that the last relays in the series mightnot be operated, or may be in the process of being operated, while thefirst relay A5 is in the process of being restored. That is, relay A5may restore in such a short time that the succeeding relays in theseries may not have had sumcient time within which to be operated.Particularly is this so, when the circuit is extended to a large numberof steps beyond the basic two relay circuit; Regardless of this fact,however, cycle timing of each of the relays by alternate discharge and.charge of the condenser as will continue as long as the start relay S5is held operated.

An advantage of extended arrangements of the basic circuits of theinvention is that a reduction in the number of elements may beaccomplished by utilizing elements common to more than one relay. Anexample of such a common element is resistance 52 in theenergizingcircuit for the windings of alternate relays B5 and D5. This combinationto eliminate one resistance element is accomplished merely by joiningthe normally open contacts of the make-before-break contact sets of theenergizing circuits with which the resistance is associated. Resistance53 could likewise be made a common element for a number of relays. Thus,it is apparent that a pair of such current limiting resistances asresistances 52 and 53 may be made to function satisfactorily for all therelays of a multi-step timing circuit.

Although the interrupters herein disclosed are not shown as they mightbe applied in actual use in conjuction with specific apparatus, it willbe readily apparent to those skilled in the art that with the provisionof the work contacts I on each of the timing relays, the interrupterswill readily lend themselves to numerous applications in circuit design.For example, the basic two-step circuits find application in conjunctionwith apparatus requiring periodic interruption of circuit continuity asfor busy tone signalling in telephone systems, or pulsing of voltagesfor purposes such as signal lamp flashing or pulse generation. Inaddition, any of the basic two step circuits might be extended intocircuits having four or more relays, as related above, to make theinterrupters adaptable to even a much wider range of application.

I claim:

1. In combination, a series comprising an even number of normallyrestored electromagnetic relays each having normally open contacts andnormally closed contacts controlled thereby, a source of direct current,a control condenser, meansfor establishing respective operatingcircuitsfor the relays successively, the operating circuit of the firstrelay excluding all contacts of the first relay but including normallyclosed contacts of the last relay, the operating circuit of each relaysucceeding the first including normally open contacts of the immediatelypreceding relay, means for establishing respective holding circuits forthe relays successively, each holding circuit including said condenserand normally open contacts of its own relay, the holding circuit of eachrelay succeeding the first including normally closed contacts of theimmediately preceding relay, whereby the restoration of each relayreceding the last closes the holding circuit and opens the operatingcircuit or" the next succeeding relay, the holding circuit of eachalternate relay, when closed, including said current source in serieswith the condenser, whereby the con denser charges therein, the holdingcircuit of each remaining relay, when closed, excluding said currentsource, whereby the condenser discharges therein.

2. In combination, a series comprising an even number of normallyrestored electromagnetic relays each having normally open contacts andnormally closed contacts controlled thereby, a source of direct current,a control condenser having one terminal connected to one pole of thecurrent source leaving one free terminal, means for establishingrespective operating circuits for the relays successively, the operatingcircuit of the first relay excluding all contact of the first relay butincluding normally closed contacts of the last relay, the operatingcircuit of each relay succeeding the first including normally opencontacts of the immediately preceding relay, means for establishingrespective holding circuits for the relays successively, each holdingcircuit including normally'op'en contacts of its own relay connectedbetween the free terminal of said condenser and the winding of theconcerned relay, the holding circuit of each relay succeeding the firstalso ineluding normally closed contacts of the immediately precedingrelay, whereby said condenser is successively connected in the holdingcircuit of each relay of the series upon closure of the holding circuitof each such relay responsive to restoration of the immediatelypreceding relay, the holding circuit of each alternate relay, whenclosed, including said current source in series with the condenser,whereby the condenser charges therein, the holding circuit of eachremaining relay, when closed, excluding said current source, whereby thecondenser discharges therein.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Y Date 2,080,273 Holmes May 11, 1937 2,347,48l Hooven Apr. 25, 19442,473,683 Hines June 21, 1949

